Re: [Tutor] Still Trying to Understand GAE
Thankyou all, you're very precious for me. yeah it seems the development webserver (and the production one) are importing modules in a non-standard way. I absolutely don't understand this choice. Why import everything everytime? Don't you think it makes scripts much more slow? Giorgio 2009/9/16 Kent Johnson ken...@tds.net: On Sun, Sep 13, 2009 at 9:59 AM, ad...@gg-lab.net ad...@gg-lab.net wrote: Hi All, i've started earning python sone months ago (on Google App Engine unfortunately). I have some doubts reagrding import, and have asked a similar question here months ago, but without finding a solution. So: with import i can import modules or single functions. And this is ok. Then: as i have understood from all the books i readm in each package directory i have the __init__.py file that decides what import with it. In other words if my package skel is like: /gg/ /gg/sub1/ /gg/sub1/file.py /gg/sub2/ /gg/sub2/file.py and i use import gg, nothing is imported. To import sub1 and sub2, i can: - Put in /gg/ a __init__.py file that tells to import them - Use from gg import sub1 Ok now the $1 Billion question: google app engine has the same schema than my gg package, an empty __init__.py file, but if i use import google it also imports all subdirectories. And i can't understand wiìhy it does so. In general, import foo does not import subpackages of foo unless they are specifically imported in foo/__init__.py, so dir(foo) will not show the subpackages. However if you import foo import foo.bar then dir(foo) will include 'bar'. Here is an example from the std lib: In [1]: import distutils In [2]: dir(distutils) Out[2]: ['__builtins__', '__doc__', '__file__', '__name__', '__package__', '__path__', '__revision__', '__version__'] In [3]: import distutils.cmd In [4]: dir(distutils) Out[4]: ['__builtins__', '__doc__', '__file__', '__name__', '__package__', '__path__', '__revision__', '__version__', 'archive_util', 'cmd', 'dep_util', 'dir_util', 'errors', 'file_util', 'log', 'spawn', 'util'] My guess is that the startup for GAE is importing the subpackages so they then appear as imported modules. To access your sub-package, just import it normally. Kent ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Still Trying to Understand GAE
On Thu, Sep 17, 2009 at 8:38 AM, ad...@gg-lab.net ad...@gg-lab.net wrote: Thankyou all, you're very precious for me. yeah it seems the development webserver (and the production one) are importing modules in a non-standard way. I absolutely don't understand this choice. Why import everything everytime? Don't you think it makes scripts much more slow? My guess is that they are importing what they need. It does impact startup but hey, if you need it, you need it. Try this for comparison: Start Python from a command line, then In [5]: import sys In [6]: len(sys.modules) Out[6]: 323 I have IPython loaded so this number may be larger than yours. In Python 3, with no IPython, I get import sys len(sys.modules) 47 So my advice is, don't worry about it. Kent ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Still Trying to Understand GAE
Yes Kent, i'm not worrying about it, i was just trying to find the reason why they're doing so. Anyway, i'm a newbye, but the GAE Evinronment is very very difficult to understand. The only thing is thas in common with the real python is the sintax. Thankyou again 2009/9/17 Kent Johnson ken...@tds.net: On Thu, Sep 17, 2009 at 8:38 AM, ad...@gg-lab.net ad...@gg-lab.net wrote: Thankyou all, you're very precious for me. yeah it seems the development webserver (and the production one) are importing modules in a non-standard way. I absolutely don't understand this choice. Why import everything everytime? Don't you think it makes scripts much more slow? My guess is that they are importing what they need. It does impact startup but hey, if you need it, you need it. Try this for comparison: Start Python from a command line, then In [5]: import sys In [6]: len(sys.modules) Out[6]: 323 I have IPython loaded so this number may be larger than yours. In Python 3, with no IPython, I get import sys len(sys.modules) 47 So my advice is, don't worry about it. Kent ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Still Trying to Understand GAE
ad...@gg-lab.net wrote: The google directoy has an empty __init__.py file (well, if we want to be completely correct it contains some commented -#- lines). Same for appengine, net and pyglib. As they all have an __init__.py file, they should be consiedered as modules from the python interpreter. So, if i run import google it imports all google's submodules. Well, now, the problem: if i create another directory (module) in the google dir, it doesn't get imported. Of course i've put in it some .py files and an empty __init__.py file. I would guess that additions have been made to the list of modules in sys.path. Where the code that is making these additions is located is another matter. Often, people manipulate sys.path from within __init__.py files but, as you have seen, this isn't the case for the google package - all the __init__.py are empty. To verify, navigate to the GAE directory, the one containing the 'google' package, and start a python interactive session. Then do --- import google --- dir(google) You don't get 'appengine', 'net' etc. in the output. So the google package *is* the same as your own package. The confusion is probably coming from the fact that you are doing your imports from 'within' an already running process - the appserver, and this process has had a chance to manipulate sys.path before your code runs. Look at dev_appserver.py in the sdk and google/appengine/tools/dev_appserver.py - don't ask me what that code is doing, but perhaps there is a clue there, let us know if you find it! Regards ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Still Trying to Understand GAE
On Sun, Sep 13, 2009 at 9:59 AM, ad...@gg-lab.net ad...@gg-lab.net wrote: Hi All, i've started earning python sone months ago (on Google App Engine unfortunately). I have some doubts reagrding import, and have asked a similar question here months ago, but without finding a solution. So: with import i can import modules or single functions. And this is ok. Then: as i have understood from all the books i readm in each package directory i have the __init__.py file that decides what import with it. In other words if my package skel is like: /gg/ /gg/sub1/ /gg/sub1/file.py /gg/sub2/ /gg/sub2/file.py and i use import gg, nothing is imported. To import sub1 and sub2, i can: - Put in /gg/ a __init__.py file that tells to import them - Use from gg import sub1 Ok now the $1 Billion question: google app engine has the same schema than my gg package, an empty __init__.py file, but if i use import google it also imports all subdirectories. And i can't understand wiìhy it does so. In general, import foo does not import subpackages of foo unless they are specifically imported in foo/__init__.py, so dir(foo) will not show the subpackages. However if you import foo import foo.bar then dir(foo) will include 'bar'. Here is an example from the std lib: In [1]: import distutils In [2]: dir(distutils) Out[2]: ['__builtins__', '__doc__', '__file__', '__name__', '__package__', '__path__', '__revision__', '__version__'] In [3]: import distutils.cmd In [4]: dir(distutils) Out[4]: ['__builtins__', '__doc__', '__file__', '__name__', '__package__', '__path__', '__revision__', '__version__', 'archive_util', 'cmd', 'dep_util', 'dir_util', 'errors', 'file_util', 'log', 'spawn', 'util'] My guess is that the startup for GAE is importing the subpackages so they then appear as imported modules. To access your sub-package, just import it normally. Kent ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Still Trying to Understand GAE
Hi Wesley! Thankyou very much for your mail (and i'd like to thankyou in a special way for your corrections :) ). it imports all sub*packages*. don't think directories because the import mechanism doesn't work this way. this is likely because there are __init__.py files in those subdirectories. another possibility is that there are non-empty __init__.py files that do the imports of things that you're not expecting. Ok, i've checked all those files, because in a standard python evinronment the __init__.py is the only file that can decide what to import. If you want to check directly, here you can find the SDK. Just open the google directory. http://googleappengine.googlecode.com/files/google_appengine_1.2.5.zip As i've said, this simple script: --- #!/usr/bin/python import google print Content-Type: text/html print print head print /head print body print google,dir(google) print /br print /br print /body --- Gives this output: google ['__builtins__', '__doc__', '__file__', '__name__', '__package__', '__path__', 'appengine', 'net', 'pyglib'] The google directoy has an empty __init__.py file (well, if we want to be completely correct it contains some commented -#- lines). Same for appengine, net and pyglib. As they all have an __init__.py file, they should be consiedered as modules from the python interpreter. So, if i run import google it imports all google's submodules. Well, now, the problem: if i create another directory (module) in the google dir, it doesn't get imported. Of course i've put in it some .py files and an empty __init__.py file. Thankyou again! Giorgio 2009/9/13 wesley chun wes...@gmail.com: hi Giorgio, welcome to Python (whether directly or from GAE!) :-) my comments below. with import i can import modules or single functions. And this is ok. not quite true. regardless of whether you use import or from-import, you're *always* importing (and loading) modules or packages in their entirety. now, whether you have *access* to entire modules/packages or individual attributes (functions, classes, or standard data), is another matter -- usually this is a result of using from-import. also, the difference between importing and loading is that loading only happens the first time you import a module/package. (if you do it more than once, e.g., module A imports B and C and module B also imports C, the import of C happens twice but the loading happens only once. if i use import google it also imports all subdirectories. And i can't understand wiìhy it does so. it imports all sub*packages*. don't think directories because the import mechanism doesn't work this way. this is likely because there are __init__.py files in those subdirectories. another possibility is that there are non-empty __init__.py files that do the imports of things that you're not expecting. hope this helps! -- wesley - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Core Python Programming, Prentice Hall, (c)2007,2001 Python Fundamentals, Prentice Hall, (c)2009 http://corepython.com wesley.j.chun :: wescpy-at-gmail.com python training and technical consulting cyberweb.consulting : silicon valley, ca http://cyberwebconsulting.com ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] Still Trying to Understand GAE
Hi All, i've started earning python sone months ago (on Google App Engine unfortunately). I have some doubts reagrding import, and have asked a similar question here months ago, but without finding a solution. So: with import i can import modules or single functions. And this is ok. Then: as i have understood from all the books i readm in each package directory i have the __init__.py file that decides what import with it. In other words if my package skel is like: /gg/ /gg/sub1/ /gg/sub1/file.py /gg/sub2/ /gg/sub2/file.py and i use import gg, nothing is imported. To import sub1 and sub2, i can: - Put in /gg/ a __init__.py file that tells to import them - Use from gg import sub1 Ok now the $1 Billion question: google app engine has the same schema than my gg package, an empty __init__.py file, but if i use import google it also imports all subdirectories. And i can't understand wiìhy it does so. Can you help me? Thankyou Giorgio ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Still Trying to Understand GAE
hi Giorgio, welcome to Python (whether directly or from GAE!) :-) my comments below. with import i can import modules or single functions. And this is ok. not quite true. regardless of whether you use import or from-import, you're *always* importing (and loading) modules or packages in their entirety. now, whether you have *access* to entire modules/packages or individual attributes (functions, classes, or standard data), is another matter -- usually this is a result of using from-import. also, the difference between importing and loading is that loading only happens the first time you import a module/package. (if you do it more than once, e.g., module A imports B and C and module B also imports C, the import of C happens twice but the loading happens only once. if i use import google it also imports all subdirectories. And i can't understand wiìhy it does so. it imports all sub*packages*. don't think directories because the import mechanism doesn't work this way. this is likely because there are __init__.py files in those subdirectories. another possibility is that there are non-empty __init__.py files that do the imports of things that you're not expecting. hope this helps! -- wesley - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Core Python Programming, Prentice Hall, (c)2007,2001 Python Fundamentals, Prentice Hall, (c)2009 http://corepython.com wesley.j.chun :: wescpy-at-gmail.com python training and technical consulting cyberweb.consulting : silicon valley, ca http://cyberwebconsulting.com ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
